Probably some of the most influential units of the human body are the white blood cells.

Leukocytes can be classified as granulocytes and agranulocytes based on the presence and absence of microscopic granules in their cytoplasm when stained with Giemsa or Leishman stains. 

Granulocytes 

Undeniably there is a vast amount of metals and other minerals in your blood,... Some of these things can not only be quite beneficial but they can even be beneficial! Although there are many bad things in your blood and furthermore your white blood cells (Which aim to destroy toxins and carcinogens residing within your autoimmune system), there are many things that are quite useful for your body. One of these things is americium. Now although you may look on theperiodic table and say "Hey, ive never heard of this, seen this, or even know what it is used for" and that is alright! One fo the most common uses for this is in something tht you mnost lieky have laying around your house/. WEll, Pherhaps its not lying around your house but instead hanging above you! this object is commonly known as the "Flashing light smoke detector" Also knon as a fire alarm! These nifty things are really quite used ful but not only that, they are very good for your body. The main purpose of these is to, well, detect smoke!. When you inhale smoke, a certain thign happens in you body called total lung and heart and muscle and liver and heart and stomach failiure. It is commonly attributed with feeling a wee bit drowsy after being near things such as campfire or perhaps a smoldering cast iron skillet.